The New York State Department of Agriculture and Markets has confirmed that a Paint mare from Erie County has been diagnosed with equine herpes myeloencephalopathy (EHM), the neurologic form of equine herpesvirus-1 (EHV-1), the Equine Disease Communication Center (EDCC) reported Jan. 11.
The affected mare, who exhibited ataxia (incoordination) and fell, tested positive for EHV-1 on a nasal swab PCR test last week, the EDCC said.
“The mare and all other horses on the farm are quarantined,” the EDCC said. “Biosecurity measures and temperature monitoring are in place. No horses have left the farm in the two weeks preceding the onset of the illness nor have left the farm after the diagnosis of this case. The mare has not traveled off the farm recently.”
Also last week, officials confirmed an additional case of EHV-1 and a case of EHM in New York horses residing in Schuyler County.
Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and EHM. In many horses, the first or only sign of EHV-1 infection is fever, which can go undetected.
In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months), but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1.
Horses with the neurologic form usually have a fever at the onset of the disease and might show signs of a respiratory infection. A few days later, neurologic signs such as ataxia (incoordination), weakness or paralysis of the fore- and hind limbs, urine retention and dribbling, loss of tail tone, and recumbency (inability to rise) develop.
Herpesvirus is easily spread by nose-to-nose or close contact with an infectious horse; sharing contaminated equipment including bits, buckets, and towels; or clothing, hands, or equipment of people who have recently had contact with an infectious horse. Routine biosecurity measures, including hygiene and basic cleaning and disinfection practices, should be in place at all times to help present disease spread.
Current EHV-1 vaccines might reduce viral shedding but are not protective against the neurologic form of the disease. Implementing routine biosecurity practices is the best way to minimize viral spread, and the best method of disease control is disease prevention.